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2 μm人眼安全波段太阳光抽运激光器的理论研究

林学彤 杨苏辉 王欣 李卓 张金英

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2 μm人眼安全波段太阳光抽运激光器的理论研究

林学彤, 杨苏辉, 王欣, 李卓, 张金英

Theoretical study of eye-safe 2 μm laser directly pumped by sunlight

Lin Xue-Tong, Yang Su-Hui, Wang Xin, Li Zhuo, Zhang Jin-Ying
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  • 太阳光直接抽运激光器在空间光通信、遥感等领域有着重要的潜在应用, 但是一直以来人们对太阳光抽运激光器的研究局限于以掺Nd3+粒子为增益介质的1 μm波段. 通过对现有固体激光工作物质的吸收谱进行分析, 发现掺Tm3+离子在太阳辐射较强的可见光波段具有强的吸收峰, 使2 μm人眼安全波段实现太阳光直接抽运激光输出成为可能. 本文对Tm:YAG和Tm:YAP两种常见晶体的吸收谱与太阳光谱匹配度进行了分析计算, 得出两种材料用于太阳光抽运激光器的阈值抽运功率密度分别为1.14和1.434 kW/cm3. 选择与抽运阈值功率密度低的Tm:YAG晶体作为增益介质, 使用TracePro软件建立太阳光抽运激光器的二级抽运模型, 并对模型进行优化, 得到了锥形腔窗口与菲涅耳透镜的最佳距离、晶体棒的最佳长度以及锥形腔最佳锥度. 本文的工作为实现太阳光直接抽运2 μm激光输出做了理论上的准备.
    Solar energy has become one of the new types of energy sources for humanity in the future due to its abundant recourse, clean use and huge reserve. Solar-pumped laser has potential applications in free space optical communications, remote sensing and other fields. However, the research on solar-pumped laser is limited to 1 μm band with neodymium-doped material as a gain medium. To expand the output wavelength range of solar-pumped solid-state lasers, thereby expanding their application fields is one of the goals pursued by researchers in the field. According to the analysis of the absorption spectra of existing solid laser materials, we find that the thulium-doped crystals also have strong absorption peaks in visible light band where solar radiation is strong. Therefore, it is possible that solar-pumped laser could also generate output at 2 μm eye-safe wavelength. In this paper, the absorption spectrum and spectral matching of two common laser crystals—Tm:YAG and Tm:YAP with solar spectrum are analysed and calculated. According to the quasi-three-level transition rate equation of thulium ion and the model of solar-pumped laser system, we obtain the theoretical threshold pump power densities of these two crystals to be 1.14 kW/cm3 and 1.434 kW/cm3, respectively. We choose the Tm:YAG crystal with lower threshold pump power density as the gain medium and built a two-stage pumping model with TracePro software. In our model, Fresnel lens is the primary solar light concentrator, and a conical cavity with diffusion reflection surface is used as a secondary concentrator to couple the solar energy to laser crystal. Laser setup parameters such as the distance between the Fresnel lens and the window of conic cavity, length of crystal, taper of conic cavity are optimized with the model. The work in this paper offers a valuable reference for future experimental research of 2 μm solar-pumped laser. Finally, we point out the challenge of the future work. Special attention needs to be paid to the huge thermal effect caused by a large amount of sunlight shining on the Tm:YAG crystal. We could find a new kind of diffuse reflection coolants or use thermally bonded crystals to mitigate thermal effects. It will be the focus of future work.
      通信作者: 杨苏辉, suhuiyang@bit.edu.cn
    • 基金项目: 国家自然科学基金(批准号: 61835001, 61875011)资助的课题
      Corresponding author: Yang Su-Hui, suhuiyang@bit.edu.cn
    • Funds: the National Natural Science Foundation of China (Grant Nos. 61835001, 61875011)
    [1]

    Shi J, Wang H, Qian J, He X 2016 Opt. Commun. 363 21Google Scholar

    [2]

    Zhu X, Lu Z, Wang Y 2015 Laser Part. Beams 33 11Google Scholar

    [3]

    Kavaya M J, Beyon J Y, Koch G J, Petros M, Petzar P, Singh U N, Trieu B C, Yu J 2014 J. Atmos. Ocean. Tech. 31 826Google Scholar

    [4]

    Wagener T J, Demma N, Kemetec J D, Kubo T S 1995 IEEE Aero. El. Sys. Mag. 10 23

    [5]

    Marano M, Galzerano G, Svelto C, Laporta P 2004 IEEE T. Instrum. Meas. 53 571Google Scholar

    [6]

    Koch G J, Beyon J Y, Petzar P, Petros M, Yu J, Trieu B C, Kavaya M J, Singh U N, Modlin E A, Bames B W, Demoz B B 2010 J. Appl. Remote Sens. 4 043512Google Scholar

    [7]

    Koch G J, Beyon J Y, Bames B W, Petros M, Yu J, Amzajerdian F, Kavaya M J, Singh U N 2007 Opt. Eng. 46 16201

    [8]

    Geisthoff U W, Zenk J, Steinhart H, Iro H 2001 HNO 49 194Google Scholar

    [9]

    Ma Q L, Bo Y, Zong N, Pan Y B, Peng Q J, Cui D F, Xu Z Y 2011 Opt. Commun. 284 1645Google Scholar

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    Young C G 1966 Appl. Opt. 5 993Google Scholar

    [11]

    Thompson G A, Krupkin V, Yogev A 1992 Opt. Eng. 31 2644Google Scholar

    [12]

    Yabe T, Ohkubo T, Uchida S, Yoshida K, Nakatsuka M, Funatsu T, Mabuti A, Oyama A, Nakagawa K, Oishi T, Daito K, Behgol B, Naayama Y, Yoshida M, Motokoshi S, Sato Y, Baasandash C 2007 Appl. Phys. Lett. 90 261120Google Scholar

    [13]

    Saiki T, Funahashi K, Motokoshi S, Imasaki K, Fujioka K, Fujita H, Nakatsuka M, Yamanaka C 2009 Opt. Commun. 282 614Google Scholar

    [14]

    Saiki T, Motokoshi S, Imasaki K, Nakatsuka M, Yamanaka C, Fujioka K, Fujita H 2009 Opt. Commun. 282 936Google Scholar

    [15]

    杨扬 2007 博士毕业论文 (上海: 上海交通大学)

    Yang Y 2007 Ph. D. Dissertation (Shanghai: Shanghai Jiao Tong University) (in Chinese)

    [16]

    O'Hare J M, Donlan V L 1976 Pyhs. Rev. B 14 3732Google Scholar

    [17]

    Beyatli E, Sumpf B, Demirbas U 2019 Appl. Opt. 58 2973Google Scholar

    [18]

    赵彬, 赵长明, 何建伟, 杨苏辉 2007 光学学报 27 1797Google Scholar

    Zhao B, Zhao C M, He Z W, Yang S H 2007 Acta Opt. Sin. 27 1797Google Scholar

    [19]

    方容川 2001 固体光谱学 (合肥: 中国科学技术大学出版社) 第4页

    Fang R C 2001 Solid State Spectroscopy (Vol. 1) (Hefei: Press of University of Science and Technology of China) p4 (in Chinese)

    [20]

    赵立伟 2010 硕士毕业论文 (北京: 北京理工大学)

    Zhao L W 2010 M. S. Dissertation (Beijing: Beijing Institute of Technology) (in Chinese)

    [21]

    徐鹏 2019 博士毕业论文 (北京: 北京理工大学)

    Xu P 2019 Ph. D. Dissertation (Beijing: Beijing Institute of Technology) (in Chinese)

  • 图 1  太阳光谱曲线

    Fig. 1.  Curve of solar spectrum.

    图 2  太阳光谱与Tm:YAP, Tm:YAG吸收谱 (a) Tm:YAG; (b) Tm:YAP

    Fig. 2.  Matching curve of crystals and solar spectrum: (a) Tm:YAG; (b) Tm:YAP.

    图 3  Tm3+离子能级跃迁示意图

    Fig. 3.  Schematic diagram of Tm3+ ion level transition.

    图 4  (a) TracePro软件建立的太阳光抽运激光器二级抽运模型; (b)锥形腔结构图

    Fig. 4.  (a) Two-stage pumping model; (b) structure diagram of conical cavity.

    图 5  锥形腔窗口位置与接受光功率关系图

    Fig. 5.  Curve of the relationship between the position of conical cavity and the received solar power.

    图 6  100 mm晶体棒侧面抽运光分布图

    Fig. 6.  Distribution map of side pump power on 100 mm-length crystal rod.

    图 7  不同晶体长度下晶体棒轴向光辐照度分布

    Fig. 7.  Axial irradiance distribution of different-length crystals.

    图 8  不同锥度下晶体棒轴向光辐照度分布图

    Fig. 8.  Axial irradiance distribution of different-taper crystals.

    表 1  晶体光谱匹配分析结果

    Table 1.  Spectral matching analysis results of crystals.

    Active
    medium
    Doping density/cm3Absorption
    band/nm
    Irradiance in absorption
    band/W·m–2
    Percentage of solar
    radiance/%
    Tm:YAG1.261×1020 (1 at.%)360—41021.9104122.9
    456—48038.78578
    656—72084.80076
    747—81269.35269
    Tm:YAP1.965×1020 (1 at.%)360—39419.5293829.8
    450—49468.23487
    643—726108.88686
    744—83695.81626
    下载: 导出CSV

    表 2  晶体参数

    Table 2.  Crystal parameters.

    Tm:YAGTm:YAP
    Doping density/cm31.26×1020
    (1 at.%)
    1.965×1020
    (1 at.%)
    Upper level lifetime/ms10.54.4
    Boltzmann factor
    in upper level
    0.460.29
    Boltzmann factor
    in lower level
    0.0170.015
    Emission cross section/cm22.5×10–213.81×10–21
    Quantum efficiency1.81.9
    Calculation results of
    absorption coefficient
    curve: $\sum\nolimits_i { {\eta _i}\overline { {a_i} } {\lambda _i} } $/cm
    46.0069×10–751.5739×10–7
    Refractive index1.821.91
    下载: 导出CSV
  • [1]

    Shi J, Wang H, Qian J, He X 2016 Opt. Commun. 363 21Google Scholar

    [2]

    Zhu X, Lu Z, Wang Y 2015 Laser Part. Beams 33 11Google Scholar

    [3]

    Kavaya M J, Beyon J Y, Koch G J, Petros M, Petzar P, Singh U N, Trieu B C, Yu J 2014 J. Atmos. Ocean. Tech. 31 826Google Scholar

    [4]

    Wagener T J, Demma N, Kemetec J D, Kubo T S 1995 IEEE Aero. El. Sys. Mag. 10 23

    [5]

    Marano M, Galzerano G, Svelto C, Laporta P 2004 IEEE T. Instrum. Meas. 53 571Google Scholar

    [6]

    Koch G J, Beyon J Y, Petzar P, Petros M, Yu J, Trieu B C, Kavaya M J, Singh U N, Modlin E A, Bames B W, Demoz B B 2010 J. Appl. Remote Sens. 4 043512Google Scholar

    [7]

    Koch G J, Beyon J Y, Bames B W, Petros M, Yu J, Amzajerdian F, Kavaya M J, Singh U N 2007 Opt. Eng. 46 16201

    [8]

    Geisthoff U W, Zenk J, Steinhart H, Iro H 2001 HNO 49 194Google Scholar

    [9]

    Ma Q L, Bo Y, Zong N, Pan Y B, Peng Q J, Cui D F, Xu Z Y 2011 Opt. Commun. 284 1645Google Scholar

    [10]

    Young C G 1966 Appl. Opt. 5 993Google Scholar

    [11]

    Thompson G A, Krupkin V, Yogev A 1992 Opt. Eng. 31 2644Google Scholar

    [12]

    Yabe T, Ohkubo T, Uchida S, Yoshida K, Nakatsuka M, Funatsu T, Mabuti A, Oyama A, Nakagawa K, Oishi T, Daito K, Behgol B, Naayama Y, Yoshida M, Motokoshi S, Sato Y, Baasandash C 2007 Appl. Phys. Lett. 90 261120Google Scholar

    [13]

    Saiki T, Funahashi K, Motokoshi S, Imasaki K, Fujioka K, Fujita H, Nakatsuka M, Yamanaka C 2009 Opt. Commun. 282 614Google Scholar

    [14]

    Saiki T, Motokoshi S, Imasaki K, Nakatsuka M, Yamanaka C, Fujioka K, Fujita H 2009 Opt. Commun. 282 936Google Scholar

    [15]

    杨扬 2007 博士毕业论文 (上海: 上海交通大学)

    Yang Y 2007 Ph. D. Dissertation (Shanghai: Shanghai Jiao Tong University) (in Chinese)

    [16]

    O'Hare J M, Donlan V L 1976 Pyhs. Rev. B 14 3732Google Scholar

    [17]

    Beyatli E, Sumpf B, Demirbas U 2019 Appl. Opt. 58 2973Google Scholar

    [18]

    赵彬, 赵长明, 何建伟, 杨苏辉 2007 光学学报 27 1797Google Scholar

    Zhao B, Zhao C M, He Z W, Yang S H 2007 Acta Opt. Sin. 27 1797Google Scholar

    [19]

    方容川 2001 固体光谱学 (合肥: 中国科学技术大学出版社) 第4页

    Fang R C 2001 Solid State Spectroscopy (Vol. 1) (Hefei: Press of University of Science and Technology of China) p4 (in Chinese)

    [20]

    赵立伟 2010 硕士毕业论文 (北京: 北京理工大学)

    Zhao L W 2010 M. S. Dissertation (Beijing: Beijing Institute of Technology) (in Chinese)

    [21]

    徐鹏 2019 博士毕业论文 (北京: 北京理工大学)

    Xu P 2019 Ph. D. Dissertation (Beijing: Beijing Institute of Technology) (in Chinese)

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  • PDF下载量:  64
  • 被引次数: 0
出版历程
  • 收稿日期:  2019-12-27
  • 修回日期:  2020-01-27
  • 刊出日期:  2020-05-05

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